This project is a coordinated chemical and immunochemical study of the cell-surface, peptido-polysaccharide antigens of some pathogenic yeasts and the specificity of the immune response to these antigens. Polysaccharide-protein complexes from Cladgsporium werneckii and Sporothrix schenckii have been isolated and purified. Their structures have been analyzed in detail. Immunochemical studies on these antigens with particular emphasis on identifying the portions of the molecules involved in the humoral and cellular immune responses will be carried out. A study of the possible relationship between the human pathogen, Sporothrix schenckii and a group of saprophytic fungi of the genus Ceratocystis will also be pursued. This will consist of an investigation of the fine structure of the rhamnoamannans from these organisms as an aid to understanding the difference between pathogenic and non-pathogenic organisms.